Instrument gauges, such as those used in truck instrument panels for decades, have typically been individual component assemblies (case gauges) that are attached to an instrument panel plate by way of U-shaped clamps and retaining fasteners. Electrical connection to a particular gauge is accomplished with individual wires from battery voltage, from ground, and from a remote sensor that is matched to the characteristics of that particular gauge. These wires are secured to the gauge with fasteners and lock washers. This type of design is still used quite often in many of today's new trucks.
Replacement of a failed gauge requires extensive disassembly of the instrument panel plate using certain tools to release the fasteners and clamps that hold the gauge to the plate. Other tools are required to release the fasteners holding the wires to the gauge. Reinstalling a new gauge requires that the proper wire be placed on the correct terminal, or use of the gauge could be rendered inoperable or in some cases damaged beyond repair.
In recent years, instrument panel gauges have begun being packaged in containers or cluster packs that hold more than one gauge. Similar problems, though less in magnitude, still exist for cluster assemblies when a gauge needs to be replaced. Front covers require tools to open up the pack so that a defective gauge may be replaced. In some cases, additional fasteners are used to retain the gauge to the cluster housing.
The present invention relates to a new and unique means for mounting a gauge on an instrument panel by means of a bezel so that it becomes possible for a gauge to be serviced more expediently and without the extensive use of assembly and disassembly tools and procedures that characterizes earlier servicing of instrument panel gauges.
The use of what may be called a turn lock bezel for mounting an instrumentation gauge in an instrument panel is not broadly new. It is known to use a turn lock bezel to trap a plastic lens on an individual case gauge housing. The gauge with which the known turn lock bezel is used is nevertheless still mounted with clamps and fasteners to an instrument panel plate. The gauge movement and wire connections are mated to the housing case with more individual fasteners.
The turn lock bezel of the present invention is well-suited for use with plug-in type instrumentation gauges, and for servicing allows such a plug-in type gauge to be extracted from the instrument panel along with the bezel when the bezel is turned to one of several particular circumferential positions and pulled away from the instrument panel. In a first embodiment of the present invention, there are a total of three particular circumferential positions to which the turn lock bezel can be turned, including the one position just mentioned. In another of these three circumferential positions, the turn lock bezel can be removed from the instrument panel by itself, but without also extracting the gauge. Removal of the bezel by itself without the gauge may be desirable for different reasons, such as making it easier for the window of the bezel to be cleaned. When the turn lock bezel is operated to still another of these three circumferential positions, it securely locks the gauge and itself on the instrument panel.
Because the turn lock bezel can be operated to any of the various circumferential positions simply by turning without the use of additional tools, faster and less costly servicing procedures become possible. There is also less possibility for accidental damage to instrument panel components than in the case of the prior gauge mountings described above because there is significantly less use of assembly and disassembly tools. When the bezel is in the position locking itself and the gauge on the instrument panel, it also both covers the exposed edge of the mounting aperture in the instrument panel and prevents the intrusion of dirt and ambient light between the instrument panel and bezel.
Other advantages of using turn lock bezels of the present invention arise in multiple-gauge clusters. In such a cluster, a decorative cover plate can be secured to a gauge housing that mounts in the instrument panel as a unit so as to guard against accidental disassembly of such unit prior to its mounting in the instrument panel. Also, because each gauge in a cluster mounts in its own mounting aperture independently of the others in their own mounting apertures, an adverse accumulation of tolerances is apt to be less critical.
A second embodiment of the present invention is in certain respects an improvement on the first embodiment. For any of various reasons, such as space constraints or aesthetic considerations, certain bezels are relatively shallow, meaning that their axial dimension, or thickness, is sufficiently thin that they are difficult to manually grasp for turning. Moreover, they may have a low friction surface. For example, a shallow bezel having a smooth chromed surface may cause a person's fingers to tend to slip off the bezel as he or she attempts to turn it. An improved grip for turning the bezel may be achieved by incorporating shallow molded-in axial grooves in the radially outer surface of the bezel ring, i.e. grooves that are perpendicular to the housing faceplate.
A further consideration in facilitating extraction of a gauge using a turn lock bezel according to the present invention involves the friction force with which the electrical terminals that project rearwardly from the back of the gauge engage mating terminals on a printed circuit board that provides the electrical connections to the gauge. If relatively significant forces exist, they will require that the person extracting the gauge by means of the turn lock bezel apply a sufficiently large extraction force in order to overcome these forces.
A further improvement that is provided by the second embodiment of turn lock bezel of the present invention relates to assuring a certain amount of axial lost motion between the bezel and the gauge during the extraction process that was not present in the first embodiment and that results in the rear edge of the bezel ring becoming sufficiently spaced from the face of the instrument panel housing that the person's finger tips can grip this rear edge before the friction force of disengaging the gauge terminals from those on the printed circuit board are encountered. Providing this axial lost motion that allows the bezel ring to be so positioned before the gauge itself begins to be extracted significantly facilitates the gauge extraction to an extent that is calculated to assure that the entire gauge extraction operation is performed solely by hand. By contrast in an embodiment where there is at most a very small amount of such axial lost motion, or even none at all, a person may be prevented from getting a satisfactory grip on the bezel ring at the time when significant gauge extraction resistance is encountered, and as a consequence, the person may be tempted to use a tool to pry the bezel away from the instrument panel housing. The use of a procedure that involves a prying tool is to be discouraged because of the possibility of causing accidental damage. The second embodiment of the invention is intended to avoid any temptation for the person to use a prying tool in the manner just hypothecated.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which are accompanied by drawings. Such drawings present two embodiments of the invention, in presently preferred forms, and in accordance with the best mode contemplated at this time for carrying out the invention.